Size of nearby cold clouds controlling Sun–cloud crossing duration

Determine the size distribution and morphology of the Local Ribbon of Cold Clouds, including the Local Lynx of Cold Clouds, to constrain the duration of the Sun’s crossing and the corresponding period of Earth’s exposure to enhanced radiation.

Background

The duration of Earth’s exposure to elevated heliospheric energetic particles (HEPs) and galactic cosmic rays (GCRs) during cold-cloud encounters depends critically on the physical size of the clouds encountered by the Sun.

The authors emphasize that only the Local Leo Cold Cloud has been well studied, and the broader LRCC/LxCC environment remains poorly constrained; they highlight that the clouds may be small, sheet-like, or filamentary, but their sizes are as yet unknown.

References

The duration of the crossing will depend largely on the as- yet-unknown size of these clouds.

— Increased and Varied Radiation during the Sun's Encounters with Cold Clouds in the last 10 million years  (2601.11785 - Opher et al., 16 Jan 2026) in Conclusions and Discussion